Elastic coupler

ABSTRACT

In order to make it possible to improve a durability of a cord wound around a connection element and to downsize a cord wound portion, in an elastic coupling structured such that connection elements connected to a drive side yoke and connection elements connected to a driven side yoke are alternately arranged on a circumference, cords are wound around every the mutually adjacent connection elements so as to form a band shape, and the connection elements and the cords are coated by an elastic material, single yarn having a twist number of 10 times per 10 cm or less is used as the cords.

TECHNICAL FIELD

[0001] The present invention relates to an elastic coupling which isused as a flexible joint in a motor vehicle drive system or the like.

BACKGROUND ART

[0002] In conventional, as shown in FIG. 6, there has been known anelastic coupling 51 in which connection elements 52 connected to a driveside yoke in a rotation drive system of a motor vehicle and connectionelements 53 connected to a driven side yoke are alternately arranged ona circumference, cords 54 and 55 are wound around every mutuallyadjacent connection elements 52 and 53 so as to form a band shape, andthe connection elements 52 and 53 and the cords 54 and 55 are coated byan elastic material 56 such as a rubber or the like (for example, referto Japanese Patent Publication No. 7-33852).

[0003] However, in this conventional elastic coupling 51, two foldedyarn (total of about 3000 tex) obtained by bundling two of single yarn57 having about 1500 tex as shown in FIG. 7 is used as the cords 54 and55. In the two folded yarn, both of a number of upper twists and anumber of lower twists are about 30 to 40 times per 10 cm, a thicknessof the cords 54 and 55 in this state of two folded yarn is about φ0.7mm, and a cross sectional shape thereof is substantially a circularcross section.

[0004] Accordingly, when winding the cords 54 and 55 having thethickness and the cross sectional shape mentioned above around outerperipheries of the connection elements 52 and 53 several times over,minute gaps 58 are formed between the cords 54 and 55, as shown in FIG.8, a thick winding tends to be partly generated unless the cords arewound by an accurate feeding amount (pitch), whereby a displacement (anarrow C) of the cords 54 and 55 tends to be generated at a time ofwinding.

[0005] Further, when using the structure in the state mentioned above asit is, a particular wound portion digs into an inner peripheral side bya tensile force applied to the cords 54 and 55 at a time of transmittinga torque (an arrow D), so that a dispersion is generated in a magnitudeof the tensile force between an inner peripheral side and an outerperipheral side as well as a slack is generated in the wound portion inthe outer peripheral side. Accordingly, there is a case that adurability of the cords 54 and 55 is reduced for this cause. Further,since no slack is generated in inner peripheral portions which are incontact with cords 54 and 55 wound around the connection elements 52 and53, a disconnection is early generated, the disconnected portiongradually expands to the outer peripheral side, and there is a case thatthe cords run into a breakage.

[0006] Further, since the two folded yarn formed by further bundling thesingle yarns (bundles of filaments) with each other is conventionallyused as mentioned above, each of the filaments is arranged with acomparatively large angle with respect to a torque transmittingdirection. However, it is preferable in strength of the filament that aforce is applied to each of the filaments in a state in which each ofthe filaments is arranged in parallel to the torque transmittingdirection, and by so doing, a torque transmission rate is improved. Inregard to this point, in the case of the conventional two folded yarnmentioned above, since the overlapped filaments of the two folded yarnsare rubbed with each other with an angle, there can be considered thatstrength of the filament is reduced and durability of the filament isreduced.

[0007] The present invention is made by taking the above points intoconsideration, and an object of the present invention is to provide anelastic coupling which can improve a durability of a cord wound around aconnection element, and can downsize a cord wound portion.

DISCLOSURE OF THE INVENTION

[0008] In order to achieve the object mentioned above, in accordancewith a first aspect of the present invention, there is provided anelastic coupling, in which connection elements connected to a drive sideyoke and connection elements connected to a driven side yoke arealternately arranged on a circumference, cords are wound around everythe mutually adjacent connection elements so as to form a band shape,and the connection elements and the cords are coated by an elasticmaterial, wherein single yarn is used as the cords.

[0009] Further, in accordance with a second aspect of the presentinvention, there is provided an elastic coupling, in which connectionelements connected to a drive side yoke and connection elementsconnected to a driven side yoke are alternately arranged on acircumference, cords are wound around every the mutually adjacentconnection elements so as to form a band shape, and the connectionelements and the cords are coated by an elastic material, wherein singleyarn having a twist number of 10 times per 10 cm or less is used as thecords.

[0010] Further, in accordance with a third aspect of the presentinvention, there is provided an elastic coupling, in which connectionelements connected to a drive side yoke and connection elementsconnected to a driven side yoke are alternately arranged on acircumference, cords are wound around every the mutually adjacentconnection elements so as to form a band shape, and the connectionelements and the cords are coated by an elastic material, wherein thecords employ a cord formed by bundling a plurality of single yarn eachhaving a twist number of 10 times per 10 cm or less at bundling a twistnumber of 10 times per 10 cm or less.

[0011] Further, in accordance with a fourth aspect of the presentinvention, there is provided an elastic coupling, in which connectionelements connected to a drive side yoke and connection elementsconnected to a driven side yoke are alternately arranged on acircumference, cords are wound around every the mutually adjacentconnection elements so as to form a band shape, and the connectionelements and the cords are coated by an elastic material, wherein thecords employ a bundle of filaments having unspecified cross sectionalshapes.

[0012] Further, in accordance with a fifth aspect of the presentinvention, there is provided an elastic coupling, in which connectionelements connected to a drive side yoke and connection elementsconnected to a driven side yoke are alternately arranged on acircumference, cords are wound around every the mutually adjacentconnection elements so as to form a band shape, and the connectionelements and the cords are coated by an elastic material, wherein thecords employ a bundle of filaments having uneven cross sectional shapes.

[0013] Since the cross sectional shape of the cord which is constitutedby one or a plurality of single yarn and has zero or a small twistnumber is not a uniform shape, the gap is hardly generated between thecords even when winding the cord around the connection element, and nocatch is generated at a time of winding. Accordingly, the partiallythick winding is hardly generated. Therefore, since the cord can bewound densely in comparison with the conventional one, the displacementat a time of winding and the slack due to the digging at a time oftransmitting the torque are hardly generated, so that a uniform tensileforce is applied to a whole of the cord.

[0014] Further, since the cord is wound densely in comparison with theconventional one, an occupied cross sectional area in the case ofwinding at particular turns is reduced.

[0015] Further, as a result of the present inventors having devotedthemselves to research, it is found that the cord capable of achievingthese operations is the cord constituted by the single yarn, the cordconstituted by the single yarn having the twist number of 10 times per10 cm or less, the cord formed by bundling a plurality of single yarnseach having the twist number of 10 times per 10 cm or less at thebundling twist number of 10 times per 10 cm or less, the cordconstituted by the bundle of filaments in which the cross sectionalshapes are unspecified (noncircular cross sectional shapes), the cordconstituted by the bundle of filaments in which the cross sectionalshapes are uneven (uneven cross sectional shapes), and the like.

[0016] In this case, the present proposal includes the followingtechnical matters.

[0017] That is, in order to achieve the object mentioned above, oneelastic coupling proposed by the present application is an elasticcoupling in which drive side and driven side yokes and connectionelements (shafts and bobbins) connected to the respective yokes arearranged on a circumference by a uniform interval, cords are woundaround the mutually adjacent connection elements so as to form a bandshape, and they are coated by an elastic material (a rubber or thelike), wherein the cords are constituted by a single yarn and a twistnumber is set to 10 times per 10 cm or less. Further, the cord is formedby bundling a plurality of single yarn each having the twist number of10 times per 10 cm or less at the bundling twist number of 10 times per10 cm or less.

[0018] Further, the cord used in the elastic coupling shall be describedas follows in comparison with a reinforcing cord of a tire for a motorvehicle.

[0019] That is, the cord used in the elastic coupling has conventionallyemployed the same kind of cord as the reinforcing cord of the tire forthe motor vehicle, however, since the cord is wound flat in the case ofthe tire, the problem in the elastic coupling is not generated. Further,in the case of the tire exposed to a great deformation, increasing thenumber of twist is effective as a method of increasing a breakingelongation so as to improve a durability, however, in the case that anumber of winding stages is large such as in the elastic coupling, thelarge number of twist causes an adverse effect.

[0020] Further, since the cord (single yarn) is generally formed bybundling about 300 to 600 filaments, for example, for making a diameter(a wire diameter) thereof about 0.7 mm, in the case of bundling 600filaments for example, the diameter (a wire diameter) of the filamentbecomes about 0.028 mm. As a material of the cord (single yarn), anylon, a polyester, an aramid fiber, a carbon fiber and the like can beconsidered.

[0021] Further, in the case of the present invention, the number oftwist in the single yarn is basically zero, however, the number of twistis preferably about 0 to 5 times per 10 cm in connection with handling.About 5 times per 10 cm can prevent snag and is easily handled, and whenthe number is over about 10 times per 10 cm, a portion in which thefilaments cross to each other so as to be in contact with each other isincreased, in a state of the single yarn being wound, and there is apossibility that the filaments are rubbed with each other anddisconnected. When the number becomes over 15 times per 10 cm, afrequency of the above matter is further increased. Accordingly, thiscase is not preferable.

[0022] In the case of the present invention, since the number of twistis small, it is possible to prevent the filaments from being in contactwith each other by a great angle, a durability is improved, and each ofthe filaments is arranged in a state of being in parallel to the torquetransmitting direction, so that the durability is improved, and a torquetransmission rate is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is a front view of an elastic coupling in accordance withan embodiment of the present invention;

[0024]FIG. 2 is a cross sectional view along a line A-O-A in FIG. 1;

[0025]FIG. 3 is an enlarged view schematically showing a main portion inFIG. 2;

[0026]FIG. 4 is a partly enlarged view of a cord used in the elasticcoupling;

[0027]FIG. 5 is a graph showing results of a cord durability comparingtest;

[0028]FIG. 6 is a cross sectional view of an elastic coupling inaccordance with a conventional embodiment;

[0029]FIG. 7 is a partly enlarged view of a cord used in the elasticcoupling; and

[0030]FIG. 8 is a schematic view showing a problem in the elasticcoupling.

BEST MODE FOR CARRYING OUT THE INVENTION

[0031] Next, a description will be given of an embodiment in accordancewith the present invention with reference to the accompanying drawings.

[0032]FIG. 1 is a front view of an elastic coupling 1 in accordance withan embodiment of the present invention, and a cross sectional view alonga line A-O-A thereof is shown in FIG. 2. Further, FIG. 3 shows a mainportion in FIG. 2 in an enlarged schematic manner.

[0033] As shown in FIGS. 1 to 3, the elastic coupling 1 in accordancewith the embodiment is structured by alternately arranging connectionelements 2 connected to a drive side yoke in a rotation drive system ofa motor vehicle and connection elements 3 connected to a driven sideyoke on a circumference, winding cords 4 and 5 around every mutuallyadjacent connection elements 2 and 3 so as to form a band shape, andcoating the connection elements 2 and 3 and the cords 4 and 5 by anelastic material 6 such as a rubber or the like, and is furtherstructured as follows.

[0034] That is, first, each of the connection elements 2 and 3 isprovided with a shaft 7 which is formed in a cylindrical shape so that aconnection bolt for connecting to the yoke can be inserted to the shaft7, a sleeve 9 which is fitted to an outer peripheral side of the shaft7, and a pair of axial collars 10 and 11 which are fitted to a furtherouter peripheral side of the sleeve 9, and a bobbin 8 an outer peripheryof which the cords 4 and 5 are wound around, is formed by the sleeve 9and a pair of collars 10 and 11. Each of the collars 10 and 11 is formedin an approximately C-shape in its cross section in which an outerperipheral side is opened. A pair of collars 10 and 11 having the shapementioned above are arranged with a predetermined interval in an axialdirection, whereby there are formed three groove-like spaces 12, 13 and14 sectioned by flange portions 10 a and 11 a of the respective collars10 and 11. The drive side cord 4 bridged over one adjacent connectionelement on the circumference is wound around the center groove-likespace 12 among these three groove-like spaces 12, 13 and 14, and thedriven side cord 5 bridged over another adjacent connection element onthe circumference is wound around each of the groove-like spaces 13 and14 in both left and right sides.

[0035] Further, in the embodiment, each of the drive side cord 4 and thedriven side cord 5 is formed by a cord having a smaller twist numberthan the conventional one, by using a polyester fiber or the like as aforming material, in particular, is formed by single yarn formed bybundling filaments as shown in FIG. 4, and furthermore a single yarn 15having a twist number of 10 times per 10 cm or less, or is formed byyarn obtained by bundling a plurality of single yarn having a twistnumber of 10 times per 10 cm or less at a bundling twist number of 10times per 10 cm or less. In each of the cords 4 and 5, a cross sectionalshape is an unspecified cross sectional shape (noncircular crosssectional shape) in which the displacement at a time of winding and theslack due to the digging at a time of transmitting the torque are hardlygenerated, or an uneven cross sectional shape in which the displacementat a time of winding and the slack due to the digging at a time oftransmitting the torque are hardly generated. Further, a lower limit ofthe number of twist in the cords 4 and 5 may be zero, however, ispreferably set to about 5 times per 10 cm which does not generate thesnag.

[0036] Therefore, when winding the cords 4 and 5 having the structureand the shape mentioned above around the connection elements 2 and 3,the cords 4 and 5 can be wound more densely than the conventional one,so that the displacement at a time of winding and the slack due to thedigging at a time of transmitting the torque are hardly generated, and auniform tensile force is applied to a whole of the cords 4 and 5.Accordingly, the cords 4 and 5 are hard to be broken, whereby it ispossible to improve a durability of the cords 4 and 5. Results of acomparative test are as shown in FIG. 5.

[0037] Further, since the cords 4 and 5 are wound more densely than theconventional one, an occupied cross sectional area in the case ofwinding at particular turns is reduced. Therefore, it is possible todownsize the cord wound portion.

EFFECT OF THE INVENTION AND INDUSTRIAL APPLICABILITY

[0038] The present invention achieves the following effects.

[0039] That is, in the elastic coupling in accordance with each of theaspects of the present invention which is provided with the structurementioned above, since the cords can be wound more densely than theconventional one on the basis of the structure mentioned above, thedisplacement at a time of winding and the slack due to the digging at atime of transmitting the torque are hard to be generated, an uniformtensile stress is applied to the whole of the cords. Accordingly, thecords are hardly broken, and it is possible to improve a durability ofthe cords.

[0040] Further, since the cords can be wound more densely than theconventional one on the basis of the structure mentioned above, theoccupied cross sectional area in the case of winding at particular turnsis reduced. Accordingly, it is possible to downsize the cord woundportion.

[0041] Further, in the case of the present invention, since the numberof twist is zero or small, it is possible to prevent the filaments frombeing in contact with each other with the great angle, so that it ispossible to improve the strength of the filament and it is possible toimprove the durability. Further, since each of the filaments is arrangedin a state of being nearly in parallel to the torque transmittingdirection, it is possible to improve the strength of the filament, it ispossible to improve the durability and it is possible to improve thetorque transmission rate.

What is claimed is:
 1. An elastic coupling (1), in which connectionelements (2) connected to a drive side yoke and connection elements (3)connected to a driven side yoke are alternately arranged on acircumference, cords (4, 5) are wound around every the mutually adjacentconnection elements (2, 3) so as to form a band shape, and saidconnection elements (2, 3) and the cords (4, 5) are coated by an elasticmaterial (6), wherein single yarn is used as said cords (4, 5).
 2. Anelastic coupling (1), in which connection elements (2) connected to adrive side yoke and connection elements (3) connected to a driven sideyoke are alternately arranged on a circumference, cords (4, 5) are woundaround every the mutually adjacent connection elements (2, 3) so as toform a band shape, and said connection elements (2, 3) and the cords (4,5) are coated by an elastic material (6), wherein single yarn having atwist number of 10 times per 10 cm or less is used as said cords (4, 5).3. An elastic coupling (1), in which connection elements (2) connectedto a drive side yoke and connection elements (3) connected to a drivenside yoke are alternately arranged on a circumference, cords (4, 5) arewound around every the mutually adjacent connection elements (2, 3) soas to form a band shape, and said connection elements (2, 3) and thecords (4, 5) are coated by an elastic material (6), wherein said cords(4, 5) employ a cord formed by bundling a plurality of single yarn eachhaving a twist number of 10 times per 10 cm or less at a bundling twistnumber of 10 times per 10 cm or less.
 4. An elastic coupling (1), inwhich connection elements (2) connected to a drive side yoke andconnection elements (3) connected to a driven side yoke are alternatelyarranged on a circumference, cords (4, 5) are wound around every themutually adjacent connection elements (2, 3) so as to form a band shape,and said connection elements (2, 3) and the cords (4, 5) are coated byan elastic material (6), wherein said cords (4, 5) employ a bundle offilaments having unspecified cross sectional shapes.
 5. An elasticcoupling (1), in which connection elements (2) connected to a drive sideyoke and connection elements (3) connected to a driven side yoke arealternately arranged on a circumference, cords (4, 5) are wound aroundevery the mutually adjacent connection elements (2, 3) so as to form aband shape, and said connection elements (2, 3) and the cords (4, 5) arecoated by an elastic material (6), wherein said cords (4, 5) employ abundle of filaments having uneven cross sectional shapes.